Recovery of products of hydrocarbon conversion reactions



Feb. 22, 1949. M. H, GoRlN ETAL 2,462,334

RECOVERY OF PRODUCTS OF HYDROCARBON CONVERSION REACTIONS H. GORIN ET/AL RECOVERY 0F PRODUCTS 0F `HYDROCARBON CONVERSION REACTIONS Feb. 22, 1949.

2 Sheets-Sheet 2 MGvSSNuJ Filed Nov. 13, 1945i ST QOhQOQWSN MW mmw W m/h atentecl Feb. 22, 194@ niioovnar oFQraQniIC'rs oF HYDROCAR- eoN CONVERSION REACTIONS Manuel n'. Gerin anu' Win Tex., assignors, by mesne swerdlofi, Dalias', assignments, to

Socony-Vacilu'in Oil Company, Incorporated, New York, N. Y., a corporation of New York Application November 13, 1945, Serial No. 628,298

1 Claim.

This application is a continuation-impart of our copending application Serial No. 448,886 filed June 29, 1942 and now abandoned, and is related to our copending application Serial No. 589,850 led April 23, 1945 and now Patent No. 2,412,143, also a continuation-in-part of our application Serial No. 448,886, wherein the same subj ect matter is generally disclosed and separation of the products of hydrocarbon conversion reactions from soluble catalysts by vaporization is broadly claimed.

Thisl invention relates to low temperature hydrocarbon conversion processes such as the a1- kylation, isomerization, reforming and the like of light hydrocarbons. More particularly this invention relates to such low temperature hydrocarbon conversion processes which are carried out with the aid of hydrocarbon soluble catalysts for the particular reaction involved.

The use of hydrocarbon soluble catalysts in solution in a hydrocarbon to effect an alkylation reaction has been disclosed in copending application Serial No. 416,864, filed October 28, 1941 and now Patent No. 2,401,925, by Manuel H. Gerin, and to eiiect a reforming reaction has been disclosed in U. S. Patent 2,383,123. The use of such catalysts to effect isomerization reactions is known. The process of this invention is applicable to any low temperature hydrocarbon conversion reaction carried out with the aid of any hydrocarbon soluble isomerization, reforming or alkylation catalyst. Aluminum bromide is a particularly useful catalyst for these reactions. Examples of` other suitable catalysts of the type with which the process of this invention is concerned are dialkyl aluminum chlorides, aluminum iodide, stannic chloride, dialkyl boron halides and the like.

The hydrocarbon soluble catalysts are of value in these low temperature hydrocarbon conversion processes because of the ease with which intimate contact between the catalyst and the reactants may be obtained. Because of the excellent contact obtained between the catalysts and the reactants, no special agitating or mixing equipment is required, as is necessary where an immiscible liquid is the catalytic agent used. Likewise in vcomparison with solid catalysts a much smaller amountl of catalyst is required for the same eiciency of contacting, since there is molecular contact between catalyst and the reactants. Another advantage obtained by the use of soluble catalysts as compared with-solid or immiscible liquid catalysts'is that the concentration of the catalyst in the reaction mixture may be varied. In many of these hydrocarbon conversion reactions the same reactants may combine in diierent ways to form several products. By Varying the catalyst concentration, the reaction may be made to shift in favor of a particular reaction to give a desired product as the major product of the interaction of the particular hydrocarbon reactant mixture.

The primary problem encountered in the use of the soluble catalysts, which is not encountered in the broad sense in the case of the use of insoluble catalysts, is that of separation of the main portion of the products from the major portion of the reactants and catalysts. It is, therefore, a primary object of this invention to provide for the ready separation of product and catalyst, and for the recirculation of the latter back to the reaction mixture.

Another object of this invention is to provide a method for the separation of product and catalyst which may be carried out continuously, and which will not tie down the rate and conditions for carrying out the reaction to the rate and conditions used for the separation of product, catalyst and unreacted hydrocarbons.

Other objects of the invention will be apparent from the description thereof, and from the appended claims- The general procedure followed in carrying out the hydrocarbon conversion process which forms the subject matter of our invention is to introduce the hydrocarbon and other reactants, if required, into a reaction zone, along with a hydrocarbon soluble catalyst; withdraw a portion of the reaction mixture containing products, unchanged reactants, and dissolved catalyst to a separation zone; divide the mixture into two fractions in the separation zone, one consisting principally of a solution of catalyst in unchanged reactants and/oi' product, which is recirculated directly 'back to the reaction zone, and the other, consisting essentially of product accompanied by varying amounts of reactants, is drawn off for subsequent recovery of the product. The product in this second fraction may be separated from the unchanged reactants, and minor amounts of catalyst carried along therewith, by any suitable method, and the particular method chosen will depend to some extent on the characteristics of the product and reactants in the particular hydrocarbon is applied. Generally a fractional distillation of unchanged reactants from the product will be the most economical and the preferred method.

The method used to separate the bulk of the product from the bulk of the catalyst in the sepaconversion process to which our method ration zone is that of evaporation. A condition essential for the successful operation of the process is, therefore, that the boiling points of the catalyst and the product differ sufficiently at some pressure at Vwhichoperation of the evaporator is feasible so that one may be vaporized while the other will largely remain as a liquid. But it is n-ot strictly essential that the boiling point of the reactant or the various reactants be diiferent from the boiling points of either the product or catalyst. In those cases where `the product is lower boiling than the reactants, the process has the additional advantage of separating the product kylates are the products to be separated out.

more or less completely from the reactants, as

well as from the catalyst. Where the reactants are lower boiling than the products, suincient reactant must be vaporized to carry over the product and separate it from the catalyst. In order to facilitate the Vaporization of the product in such cases, particularly Where the product is considerably higher boiling than the reactants, a light Volatile vhydrocarbon or other inert vola- Ytileliquid or gas, `which will not react with the catalyst'used, is added to the reaction mixture as a stripping agent. This stripping agent may be` added to the reaction mixture either in the reactor, or just prior to entry into the separation zone', `or separately into the separation zone itself. The' volatilization of this added light hydro-carbon or the passage of the inert tion' zone will assist in the carrying over of the product. p

Sufficient hydrocarbons must be associated with the catalyst leaving the separation zone to keepthecatalyst in solution, and thus avoid any undesirable precipitation of the catalyst. This imposes a limit upon the amountof hydrocarbons I which may be Vaporized in the separation zone.

Qur invention may be best understood from the follpwing description thereof in conjunction with the discussion of the drawings.

In the'drawings:

Figure 1 shows diagrammatically an apparatusfor carrying out the to an alkylation reaction.

Figure 2 shows diagrammatically an apparatuslor'carrying out the invention when applied to al reforming reaction of the type in which a natural gasoline is reformed to yield a product having'a higher octane rating.

Referring to Figure V1 the principles of our invention as applied to an alkylation reaction` arershown() -Anisoparafm such as isobutane, is v fedfto reactor I through line 2, provided with puirrp3, and valve 4. Aluminum bromide, preferably in solution in? isobutane, is introduced into thereactor through line 5 provided with pump 6 and-valve 'I. An alkylating agent such as propyleneis introduced into reactor I through line, 8 provided reactionmixture after being heated is fed into the'lfevaporating concentrator II, which is progas through the separan invention when applied with pump 9 and valve It. The

viddwith heating coil I'2, to furnish part of the necessary heat of vaporization.' The product, in this; .case branched chain heptanes, is higher boiling than the unreacted reactant, isobutane, in -the reaction mixture. The mixture must be heated y 'su'iliciently to vaporize the desired amount of theheptanes. Naturally, a considerable proportion of the lower boiling isobutane vaporizes a1s`:"'In r alkylation reaction, as is well known in thejaraitl is customary to haveV aconsiderable sidreactionsof the olefin; The- Vaporizationof s of jtheisoparain reactant to Aminimiae separated overhead, and

condenser'28, recycled vialine" I5 to the reactoras heretofore described". In the .case"o'f the'a'lf kylation reaction, the product isthehirghrfl'lboilingiand is drawn oiffron'i the bottoni of the ,frac-v Spent catalyst, in the form of an insoluble complexbtwenfthe soluble catalyst and the hydrocarbons s drawnY off either :intermittently or continuously, vfrorn-v`v this isobutane helps carry over the heptanes. Because of the substantial difference in boiling points it may frequently not be desirable or necessary to have sufficient excess isobutane in the alkylation zone, because ofwthe ,increase in reactor size andcostaf'to eie'ci tl'i'e piodutevaporization to the desired exttl""This'`s particularly true where propylene or higher olen al- A stripping gas, as heretofore mentioned, may therefore be introduced either into the reactor eiiluent or the evaporating concentrator. This gas may be isobutane itself in which case part of the recycle isobutane from the final product fractionation steps would be recycled to the reactor feed and another part to the reactor elluent or concentrator. `Other paraiinic hydrocarbons as normal butane, propane, or pentanes may be used. Where a volatile liquid such as as a liquid or a gas.

part of the recycle 'excess i'sobutaneiln lirie'lm therefore be introduced intofthe reactifefiiuen in line I6 leading from'the 're'a'ztor'tt centrator," via line' I9, and line Il'.`

The higher boiling catalyst. anda suiiic amount'of hydrocarbons to keep'it in sluti"" flow from evaporator I I back V'torea'ctoiV Invia linev 2D, after being,cooled't'rea'ctiorteinpera ture in cooler 2 I.

eeiver 24.- Theicondensafeis intrude n o fractionator 2, wherein tional-,or for storage'in tank 30.

A the bottom Iof reactor I through v'Figure 2 shows the principles applied to a typicalreformingV valve 1inei32; l

line or a light paraiiin h ydroc'arten,t'lirollfglfrlineV2A 105. The reactor eiiluent is evaporating concentrator vII sent viafline "I [I86 to.

and lower boiling hydrocarbons arevapori'aed andv carried over Via'line I i 2 and fractionator I I'I.- To secure the 4 desired 'vaporization it is usually desirable to introduce s onieH C4 hydrocarbons into the reaction mixturepriorl to their passage into the evaporator. AThe neof-Y essary C4 hydrocarbonsmay lbe introcluced froml overhead stream, into During the reforming noperationsome lineV IM, the fractionator line |08.

carbon atoms. Additionl of Cr hydroca the" sobutanejyapor" is after condensation Yin of our 'invetion Process in yhicl'i f a naturalgasolinefis reformedin the"p'resric'zeIV of asolubleV catalyst such as aluminu'i'rifboniidllf to give a product having. a 'hig'er octane.fratir'iglf' .l g 5v to-9`c'a`rbon--- isV fed into thel reactor4 [0I I- Eil-aperti@ :'IH -Y is operated under conditions yso thatthegasoline,

condenser I I3 l to I' vaporize the desired fraction without excessive heating of the reaction mixture, thus minimizing catalyst vaporization and undesirable side reactions.

The material not vaporized in evaporator mainly hydrocarbons of to 12 carbon atoms and the catalyst, is recycled via line |28, provided with cooler |29 to the reactor. In the reactor these long chain hydrocarbons reform to shorter chain carbon atom hydrocarbons.

The vapor from the evaporator passes to fractionator |I1 wherein the C4 hydrocarbons are separated from the gasoline boiling hydrocarbons, which are removed as bottoms and sent to storage tank |30. The butane vapors are condensed in condenser |32 and returned to the process to carry over more gasoline boiling product through line |24. As mentioned above, some butanes are formed in the process, and to prevent a continuous accumulation of butanes in the system, the excess butanes formed are removed through lines |40 and accumulated in storage tank |4|. Valves |42 and |43 are provided in lines |24 and |40, respectively, to control the division of ow of the butane.

The particular reactions given above in connection with the description of the drawings are by way of illustration only and are not to be construed as limiting the invention. As stated in the objects of the invention it is applicable to any low temperature hydrocarbon conversion reaction which may be catalyzed by a hydrocarbon soluble catalyst. The invention is not intended to include within its scope high temperature hydrocarbon conversion reactions such as cracking. The reactions with which this invention is concerned are generally carried on at temperatures below 150 to 200 C., although somewhat higher temperatures may be used in special cases. In general the reactions are characterized in that they do not involve the formation of appreciable amounts of fixed gases such as hydrogen, methane and ethane by decomposition and cracking of the hydrocarbons undergoing reaction.

Since the reaction with which the invention is concerned involves the use of a hydrocarbon soluble catalyst, an essential condition of the reaction is that a hydrocarbon be present in the liquid phase. It is an essential, therefore, that the rel action temperature be below the critical temperature of the hydrocarbon or hydrocarbon mixture which serves as a solvent for the catalyst. This liquid hydrocarbon is generally one of the reactants in the process, although in special cases where an inert hydrocarbon is added to serve as a carrier for the product in the separation zone, the hydrocarbon reactant or reactants may be introduced as gases for convenience andv to produce agitation of the reaction mixture in the reaction zone. v

The invention has been illustrated as applying to alkylation, reforming, and condensation reactions in general. Y

No particular type of concentrating evaporator is required for separation of the product and the catalyst. Where the product is readily volatilized a simple iiash evaporator may be used. Where a flash evaporator is used it should be provided with suitable baille plates to minimize entrainment of higher boiling hydrocarbons and catalyst in the outgoing vapors. Generally the reaction mixture being fed to the evaporator will be partially vaporized in the heater and the two phases will complete their separation in the evaporator itself. Any suitable heating coi may be inserted in the evaporator. It is generally desirable to operate the evaporator at relatively low pressure in order to reduce the temperaL ture required to vaporize the desired component tained in the liquid phase to keep the solubleV catalyst substantially completely in solution, and the substantially complete removal of the vapor phase from the vaporization zone before condensation to avoid the return of any substantial amount of the overhead to the liquid phase in the evaporator for further contact with the catalyst or to the reaction zone with the catalyst recycle. Reuxing of liqueed overhead should be avoided insofar as practicable since it will promote possible side reactions of the products as well as permit any high boiling materials, as, for example, heavy alkylate formed in an alkylation reaction to accumulate in the reaction zone.

Since these reactions are generally exothermic, suitable cooling means may be found necessary for the reaction zone to maintain the reaction temperature at the desired level. These cooling means may be the conventional cooling coils placed in or around the reactor. One method which has been found particularly useful in con trolling the temperature of the reactor is to operate at a pressure so that a portion of the reaction mixture is vaporized as a result of the exothermic heat of the reaction. 'Ihese vapors are withdrawn from the reaction zone and compressed. A portion of the compressed gases may be condensed and this condensate recirculated to the reaction zone wherein its subsequent vaporization will control the temperature by taking up excess heat of reaction. Anotherportion of this compressed gas may be recirculated to the bottom of the reaction zone and introduced through a suitable bubble plate. This gas in rising through the reaction zone will produce suicient agitation for a reaction of this type involving the use of a soluble catalvst.

Since some agitation is desirable even though. a soluble catalyst is used, it is frequently desir-` able to introduce one of the reactants, Where tw are involved, or a portion of the reactant, where only one reactant is involved into the bottom of the reactor in the gaseous phase to furnish the desired agitation. In those cases in which it is desirable to have a hydrocarbon carrier present to assist in the vaporization of the product from the catalyst in the separation zone, the catalyst may be dissolved in the hydrocarbon carrier and all of the reactant material introduced as a gas.

In the description of the invention and in the drawings, a heater has been shown interposed between the reaction zone and the separation zone to supply heat for vaporization of the product. In cases Where it is undesirable to have the vaporization temperature much or any higher than the reaction temperature the evaporator may be operated at reduced pressure to secure the necessary vaporization. Naturally some heat must be supplied in any case to supply the heat of vaporization for the product vapors and for any reactant and carrier vapors formed in the separation zone. A heating coil, placed in "theta/aparaat; W111istir-ve tdsppiy'the necessary :there arbitrator-'fand recirculateo in heat-excam :raterl feed"t eiiectfatleastpartial condensat ci* tcated'that?alternatively,I Ypart or IAallzfo'f the tevapratr-'overhead vaporsin linet2 2 'may be ine'y'i'-'and 'compressor @Wto heating :sent'vl :coil-'i342' fihe "vapor-liquid mixture formedl 'may' thenibe returned via line 31 to line 22 and to con tdensr' to-corfipiete its condensation beioreinitrodu'ction"" into Sira'ctionator 2i.4 as described :above The ie t of'fcondensat-ion of this compressed gpartfoifth Vheat necessary to evaporate the cle--A 'oheiits of theevap'oratorl reed.

the heat-,oi evaporation to the evapo-A fw'oiild? notfb'e 'i60 percent complete but it elim ate the' necessityv for additional heat for rod'tictlcontaining vapori Wiil Ysuoni-yl :the e'v'apeiatrieed; Should additional heat j ih e'ire e'saryfi'twould bea minor amount and @cui level-f evaporate '-feed; Y Y

A'smeht -previous1yin-the discussion of l a portion of the catalyst lInu-st bedrawnv off io regeneration because of theVA continuer-ts oiafccmplex between the soluble catth'e fhyd'i'ocarbonsL` Even tho'ugi'i tomjf 'he reaction Zone. This catalyst'should draw fcatail wvillthen-'be returnedA to 'the reaction zzone'. iThe"'catalyst recovery will not be le@ per .as is? ust'r'nary'in the case of catalytic reactions,

.and this make-up catalyst may be added along" 'with the regenerated catalyst. y

In the foregoing description of our invention', the process has been illustrated as applied to a :fully continuous process,` in which `the catalyst Vcontaining hydrocarbon mixture is continuousiy this di carbon vcolmo-lex"may haveA consid# cactivity, itis immiscibl'e With-the jhydccaibnand 'tends toaccumulatein the: bo'tbe and regenerated to recover the active 1i letel'anda small amount ci catalyet may e e arried'o'ver With the reaction 'prod-f' Sonie *make-up'f'catalyst Will lbe reanircd,

v supplied'at arelativelyhw temper: ture" "u"'minimiingi'the'temp-erature rise oi the withdrawn from a reactor, 'circulated to an evap'crator, and the catalyst Containing portion, Ausually the unvaporized fraction, continuously returned to the samereactor.

be preferable to use a battery of reactors YWith-a single evaporator. In such operation, the evaporater would operate continuously, but the' operation of each unit in the battery or reactors would be, strictly speaking, discontinuous. ThatV '5 is one reactor wouldbe discharging at all` times to the evaporator.

bon-'catalyst mixture Would be returning to -.another reactor, Which would also be receiving fresh' feed for reaction. The remaining reactors kin the battery Would be temporarily operating as batch reactors. When the contents of the dis-'Y charging reactor had been removed to a predetermned' extent,- 'another reactr'would be-set Frequently it may' The unvaporized hydrocar- 8" to dis'liaee to fthe evaporat porized l'r'naterial froin-v the re to adisclia'rged"fre'actorly -`Suita `e be provided to provide the desired" ope`i" a t ior'12l orcha'rgingand discharging of each:

unit"t in th ttery of nijveacntors.i` The sequence oilw operati Suche;"batteryr of reactors mightV bei.l a ser operationzw such aicase thedischarge to tfiegtevaporatb Y i'ast Areactor in the* mixture in f'hich 'the reaction'had proceeded inv ryiiig degrees toward'sco'mpletion. Any-other desir fou'E would-be a tatehrt't Arcompletelyfdisconnected from' theV if other mourn be apparentl totfhs' foref'ilf' such"Iim-itatiosshould be imposed as are indicated in the appended claim.

tations' pr our' invention will liquidi iy zoneff'reg atirigthe'jamotmt iof vaporization so that fcientfreactfion 1mixture frema'iris in the liquid fstate "ito actl asasolventffor the hydro'- carbon soluble c'ai'alfstsep''aratingthe product containiiigfivapbrfroni the 7 liquid' catalyst containing-materi'alf"compressing the-product vapor to a pressure-:at which at' least` some of VVthevapor will "czonderis'f underi'lthe"temperature conditions in vthe" separationz'one'gA passing the 'compressed vaporiri hea exchange relation ivth the material A 1\Ia`rn` ;f Datei f l Ipajtiif'et-al. Oct. 13, 1936 Grsse Jan. 2G, 1942 FebfB, 1942 Febf 29, 1944 ,f Apr. '23, 1946 2,41-2;'143"1`" Golin'et a1."' 1 Dec. 3, 1946 o'l'ildj be 'constant fromI the` series', and thmurnvaporizedi catalys containing `-nir'tlre returned to the rs'ti.

lThe internie'di'ate reactors would con l ed seqefceof operation might be *injsorheflofuyvhich each reactor unit `operatdffora` portion 'of the' time as Vnd'ffnliffperiodically vvould dis# he evaporator and "recycling of the killed 'in' the art andvther'e- 

